1. Technical Field of the Invention
This invention relates to a jack for raising vehicles, of the type known as xe2x80x9cYxe2x80x9d jacks, consisting of a support leg equipped with a foot and a vehicle support arm that turns on the support leg, in which the two upper ends of the support leg and the vehicle support arm are linked by means of a screw spindle that connects a nut in the support leg and a cross member in the vehicle support arm, with this screw spindle being turned by means of a winding handle. The movements of the screw spindle in one turning direction or the other cause the upper end of the vehicle support arm to be raised or lowered, so that by incorporating a vehicle support plate to bear the weight of the vehicle bodywork, the vehicle support arm arises or lowers the vehicle.
2. Prior Art
In certain types of jacks, made of aluminium, the vehicle support arm includes an auxiliary or reinforcing part at its upper end, which is housed inside the said vehicle support arm, as described in the publication EP. A. 0887303. In these jacks, the end of the screw spindle reaches close to the reinforcing part, more specifically through the head of the screw spindle or its riveted end portion, causing noise when the jack is in its folded position due to vibration from the vehicle being transmitted to the parts in question.
Also known through U.S. Pat. No. 1,901,915 is the existence of a nut, through which a screw spindle passes, which is included inside a U-shaped metal part which is secured to the arms of the jack.
Also known through WO. A. 99/29615 is a xe2x80x9cYxe2x80x9d type jack that includes a nut housed in the interior of a U-shaped metal part, in which the metal part is provided with some cylindrical necks that are housed in holes in the wings of the cross section of the vehicle support arm. The nut is prepared so that it does not turn inside the metal part.
In these last two references, the screw spindle passes through the nut and a hole in the base of the U-shaped metal part, so that when the jack is bearing a load, the excessive concentration of stresses takes place on the nut and against the base of the metal part, causing the nut to become unusable.
One object of the invention is to provide a vehicle jack which is equipped with a unit composed of a nut and a metal part that prevents the concentration of stresses on the nut and on the metal part, thus providing greater working life to the jack.
Another object of the invention is to provide a vehicle jack with a reinforcing part in the interior of the vehicle support arm, which does not create any kind of noise when the jack is in its folded position.
In order to achieve these objectives, the invention claims a jack provided with a nut and a U-shaped metal part through which the screw threaded spindle passes, in which the outer U-shaped body and the inner body that forms the nut itself are provided with surface areas that make contact with each other, so that when the jack is bearing a load, the incidence of the nut on the outer body is perfectly distributed.
In particular, the outer metal part is equipped with two longitudinal reinforcements that protrude out from the base of the part and extend parallel to each other towards the front opening in the said outer part. These two side reinforcement provide some vertical surface edges at their free ends which are transversally aligned and contained in the same plane.
The said surfaces form two front edges starting from the front opening in the outer U-shaped metal part.
On the other hand, the ends of the U-shaped wings of this outer part are each provided with inclined areas in a converging direction towards each other and towards the central plane of the part, in which some wide vertically aligned cavities are made. These cavities in turn each form surface areas, vertically aligned, at the bottom of the said cavities and starting from the entrance to the U-shaped body.
This outer metal part also includes two necks protruding from its wings, for insertion into the wings of the vehicle support arm, the same as in WO. A. 99/29615, as well as a hole in the centre of the base to allow the passage of the threaded screw spindle.
Meanwhile, the inner part or the one which is provided with a screw threaded hole for the insertion of the screw spindle, has some lateral projections made on the same side as the side reinforcements of the outer part, with these projections forming rear surface edges which in assembly make contact with the corresponding ones of the above mentioned reinforcements.
In the same way, this part or inner body is also provided with another two carried out in a perpendicular plane to that of the mentioned lateral projections and with these front projections vertically aligned.
The front of this inner part on side nearer the winding handle that operates the screw spindle is made with a protruding trunco-conical area.
In the assembly of the inner body into the outer one, the following circumstances take place:
The converging ends of the wings of the outer body present a certain difficult for the entry of the inner body, so that once this is housed, these ends act like clips by helping to keep the said inner body in its position.
The side surface edges of both the inner and outer bodies that provide the side reinforcements and the projections on each one remain in frontal contact.
The vertical projections on the inner body are housed in the cavities at the ends of the wings in the outer body, with surface contact also taking place between the rear sides of these projections and these cavities.
It is observed, therefore, that on the inner body being housed inside the outer one, the contact surface is increased in a longitudinal direction between both by a considerable amount, so that when the jack is bearing a load, the tendency of the inner body towards the base of the exterior one does not create any kind of overload that might disable the inner body. This body that forms the nut therefore remains preserved in its area of greater commitment of excessive concentration of stresses.
On the other hand, the inner reinforcing part housed in the interior of the vehicle support arm of the jack is provided, at its end nearer to the screw spindle, with two inclined lugs that converge towards the interior of the U-shape that forms this auxiliary part. The end or riveted portion of the screw spindle makes contact with these lugs when the jack is in its folded position, so that on forcing the winding handle of the screw spindle in order to carry our folding of the jack, pressure is placed on the said lugs, which might become deformed by the pressure exerted, although always maintaining the appropriate contact.
Therefore, this contact between the two lugs and the riveted or most forward portion of the screw spindle is ensured in its stored condition, with which any kind of unwanted noise is avoided in the jack folded position.